Cycling is a big recreational activity all around Lake Constance. Anywhere on the shore of this lake (I used to come to the German part several times a year) you see a steady stream of cyclists of all ages going by.
You can cycle all around the lake, 250 kilometers, it you want to (I haven’t done this yet), and since it is right on the shore it is pretty much flat, although this is otherwise a quite mountainous area.
There are numerous places to rent bicycles in the Austrian, Swiss and German towns all around Lake Constance. This particular one is by the lakefront in Bregenz, at the foot of Rathausstraße, not far from the harbor.
Sailing is another popular recreational activity on Lake Constance.
I must be one of the few people who has never sailed here (although I used to borrow a rowboat sometimes), but one of my sons has sailed here a lot and even has a “Bodensee Schifferpatent”, which is sort of like a driver’s license for sailing and boating on the lake.
My photos in this post are from 2005. I revised the text in 2022.